A forging device for producing a forged article is configured to obtain a forged article by placing a forging material (work) in a corresponding shaping hole formed in a lower die (die) and driving the forging material into the shaping hole by an upper die (punch) to thereby perform pressure processing of the forging material.
For example, the forging device as shown in Patent Document 1 is configured to obtain a forged article having an approximately cylindrical shape in which grooves parallel to the axial direction are formed on the outer peripheral surface thereof at equal intervals in the circumferential direction. In the forging device, groove forming protruded portions extending in the axial direction are formed on the inner peripheral side surface of the shaping hole of the die and a back pressure plate is arranged in the shaping hole. When the forging material set to the die is driven into the shaping hole by the punch, a back pressure is applied via the back pressure plate to the metallic material (metal) constituting the forging material, thereby improving the flow of the metallic material to obtain a forged article excellent in dimensional accuracy.
On the other hand, in a forging device for forming a forged article of a twisted shape having helical grooves on the outer peripheral surface thereof, a forging material is driven into a shaping hole in a screwing manner, in which helical protruded portions (blade portions) are formed on the inner peripheral side surface.